This artist's conception shows the dwarf planet Haumea, which is in the Kuiper Belt beyond Neptune. Pan-STARRS is expected to find hundreds of new Kuiper Belt Objects.

IN THE OUTER REACHES of our Solar System lies a mysterious region far more remote and difficult to explore than the Australian outback. It remains the only part of our Solar System not visited by spacecraft.

Called the Kuiper Belt, this area beyond Neptune is home to the dwarf planets Pluto, Eris, Makemake, and Haumea. It also harbours thousands of smaller objects that form a second, icy asteroid belt (or more appropriately, comet belt).

A new Earth-based telescope has begun to study this region, and already is scoring discoveries.

The Panoramic Survey Telescope & Rapid Response System (Pan-STARRS) PS1 telescope has found ten Kuiper Belt residents. Based on their brightnesses, the newfound objects range in size from 300 to 500 kilometres.

“We’re excited that Pan-STARRS is beginning to find these objects,” said Smithsonian astronomer Matthew Holman, who leads the Pan-STARRS-1 Outer Solar System Key Project.

“It marks the tip of the iceberg for future Pan-STARRS discoveries,” he added.

10 million times fainter

Pan-STARRS PS1 Observatory just before sunrise on Haleakala, Maui.

The Outer Solar System Key Project is part of a larger survey to which 60 percent of Pan-STARRS telescope time will be devoted. PS1 became fully operational in June 2010.

Over the course of the coming months and years, PS1 will repeatedly survey the full sky that is visible from its location on Haleakala, spotting objects as faint as magnitude 23 (10 million times fainter than visible to the unaided eye).

“By the end of the survey, we’ll have an essentially complete census of everything brighter than the survey’s limiting magnitude,” said Holman. This corresponds to Kuiper Belt Objects about 180 miles in diameter or larger.

Pan-STARRS will enable planetary astronomers to locate many new Kuiper Belt Objects and characterise their orbits. This will provide a firmer understanding of the structure, dynamics, and evolution of bodies in the outer Solar System.

Pan-STARRS is also likely to be a productive tool for discovering new comets.

Pan-STARRS-1 is a 1.8-metre-diameter telescope featuring the world’s largest digital camera—a 1.4-gigapixel monster that can photograph an area of the sky as large as 36 full moons in a single exposure.

Adapted from information issued by CfA. Images by CfA and Rob Ratkowski.

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